Justin Bieber has reportedly been "scolded" by the Vatican for kicking a ball around in the corridors of the Vatican Museums.

The pop star visited Rome in early October, and was given a private tour of the historic buildings, including the Papal Apartments.

But reports say Bieber, 20, had to be reprimanded for playing with a football during the tour, and also fell foul of strict codes of conduct that say no sleeveless tops, shorts or hats should be worn by visitors to the Museums, Vatican Gardens, Saint Peter's Basilica and the Sistine Chapel.

The Canadian posted a photo of himself to his Instagram account in Saint Peter's Square in the centre of Vatican City a week ago, in which he appears to be breaking such rules.

This isn't the first time Bieber has made a Vatican faux pas. In 2012, he mistakenly referred to the Sistine Chapel as the Sixteenth Chapel in an interview with David Letterman on The Late Show.

In the same year, the Vatican boasted that then-pope Benedict had set out to beat the singer on numbers of retweets from their respective followers. Pope Benedict had 2.1 million followers on Twitter at that time, only eight days after his first tweet, compared to Bieber's 31 million.

The Catholic Herald, which first reported the news, says the Vatican has declined to comment.